The present invention relates to an advancing arrangement for the stepwise advancing of a transported foil band. This foil band is precisely positioned in a processing arrangement wherein the foil band is precisely guided to a molding arrangement and a cutting or stamping arrangement in a heat forming machine. The forming maching includes an advancing mechanism which stepwise slidably advances the foil band and a scanning arrangement which controls the advancing mechanism in dependence and the coincidence of a register marking on the foil band.
In German published application No. 2254715, which corresponds to U.S. Pat. No. 3,908,331 coassigned to the assignee of the present invention there is disclosed a known advancing mechanism of the aforedescribed type. In this known arrangement two clamping mechanisms are stepwise actuated and have carrier elements which are integrally connected to each other. These carrier elements and clamping arrangement are operated by a common driving arrangement. The first clamping mechanism is longitudinally slidably mounted on its carrier element and is provided with an adjustable actuating element which is controlled by a scanning arrangement adapted to scan indicia impressed on a foil band that in turn controls the slidable advancement of the carrier element.
In this known advancing arrangement, both clamping mechanisms are disposed in the direction of advance in the foil band upstream relative to a heated region of the foil band material and also downstream from this heated region relative to the direction of the advancement of the foil band material. The clamping mechanisms are moved with the same advancing distance synchronously in a stepwise manner. In order to center the pressure-impression zone, one of the two clamping arrangements is slidably adjusted relative to the other clamping arrangement with the aid of a scanning arrangement for scanning indicia impressed on a foil band material and is stretched between both clamping mechanisms.
In this known advancing arrangement it is therefore necessary to stretch the foil band material without additionally changing anything in the stepwise advancing distance.
In this manner there can be obtained a centering of the indicia impression with respect to a stationary forming arrangement, on the condition that no changes in the foil band material occur between the forming arrangement and the cutting or stamping arrangement which is mounted at a distance of several times the distance of stepwise advancement in order to avoid the necessity of making corrections regarding the stepwise advancing distance.